Wednesday, May 27, 2015

The QTc is 423 ms. There is a large amount of ST elevation and Massive T-waves in V2 and V3, worrisome for LAD occlusion. However, there is also excellent R-wave progression.

A repeat ECG was done a short time later:

No definite change. Computerized QTc is 399 ms.

The potassium was 4.5 mEq/L.

Both of these ECGs are very worrisome for STEMI, but not diagnostic even though the second one meets criteria for STEMI (greater than 2 mm at the J-point in 2 consecutive leads). Early repolarization can look like this, however.

So the formula for differentiating acute LAD occlusion from Early repolarization was applied:

See sidebar for calculator:

The exclusions are CRITICAL(in red)

Applying the formula to ECG 1, we get 22.025. This is about 97% sensitive for LAD occlusion at a cutoff of 22.0, and 92% sensitive at a cutoff of 23.4.

If we apply to ECG 2 (which has MORE ST elevation), we get 19.63 (very low).

This ECG is so worrisome that I would not be entirely convinced that this is not MI. But I would not activate the cath lab without more information if it is a strain on resources (nighttime, weekends, for instance).

A formal echocardiogram with contrast was done and showed no anterior or apical wall motion abnormality.

The patient ruled out for MI.

Learning Points:

1. When the differential is LAD occlusion vs. Benign Early Repol, the formula may help you to rule out STEMI

2. If it is STEMI, there will be a Regional Wall Motion abnormality. If the equation indicates Early repol and you don't want to overuse scarce resources, then obtain an emergency high quality ultrasound to look for a wall motion abnormality.

Isolated ST depression in II, III, and aVF should be considered to be reciprocal to subtle ST elevation in aVL and to indicate that there is occlusion of the Diagonal, Obtuse Marginal, or even the LAD.

Initial troponin I was 0.65 ng/mL.

After she was initiated on ASA/Plavix/Heparin and Nitro, her chest pain resolved.

Time 40 minutes:

The ST depression is resolved. "Inferior" T-waves are now fully upright, consistent with reperfusion in the territory of aVL. Now there are Wellens' waves in anterolateral leads, consistent with reperfusion in the proximal LAD. This strongly suggests that while the patient was having chest pain, the proximal LAD was occluded.

Friday, May 22, 2015

I have long maintained that ST segment depression does not localize and the isolated ST depression in "inferior" leads is actually reciprocal to less obvious ST elevation in lead aVL or in "anterior" leads.

A reader alerted me to a 2010 paper that addressed this issue. They looked at all ACS cases in a CCU over a 12 year period, chose those with isolated "inferior" ST depression without any ST elevation, and found that only 10% had inferior ischemia. Most had LAD or first diagonal culprits, and most were due to occlusion or high grade thrombotic stenosis (i.e., cath lab indicated).

(The one example they showed was an LAD occlusion that would also have been identified by the LAD occlusion rules and formula).

Tuesday, May 19, 2015

A middle aged male with a history of Hypertension, Diabetes, Hyperlipidemia, and CHF due to severe concentric LVH presented with severe substernal chest pain and SOB. The blood pressure was 170/120.

There were B-lines on chest ultrasound, diagnostic of pulmonary edema.

Here is his initial ED ECG:

Sinus rhythm. There is high voltage diagnostic of LVH. With a large S-wave in V2 and V3, there should be baseline ST elevation of LVH in these leads. However, the J-point in V2 and V3 is isoelectric. This is abnormal. This is highly suggestive of relative ST segment depression.

So the previous ECG was sought:

Here we see the expected ST baseline ST elevation of LVH in V1-V3. It is proportional and appropriate.

A review of the chart showed there was an angiogram from one year prior with no significant obstructive lesions, mild plaque only. This does not rule out ACS as the etiology of ischemia, but makes it far less likely.

The patient was placed on a high dose nitro drip, and his BP dropped to 150/90. His symptoms resolved.

Another ECG was recorded 40 minutes after the first:

The relative ST depression is resolved.

The patient had a mild rise in troponin to 0.084 ng/mL which was deemed due to demand ischemia, not ACS. Of course there could possibly be ACS, but I think it is unlikely.

Learning Point:

1. An isoelectric J-point may represent ST segment depression in a patient with baseline ST elevation, and in a patient who should, due to QRS abnormalities such as LVH, have baseline ST elevation.

Sunday, May 17, 2015

This patient has a history of cardiomyopathy (EF 10%) and IVCD and heart failure and presented with altered mental status. BP was 87/52, pulse 90, saturations 100%, and respirations 14. An ECG was recorded:

There is sinus rhythm. The P-wave in V1 has a huge negative component, diagnostic of left atrial enlargement. The PR interval is 360 ms (the computer read it as 227 ms). The QRS = 134 ms, so it is an IVCD (intraventricular conduction delay), but is not LBBB because of Q-waves in I and aVL.

There is a large amount of ST elevation in V3-V5, and ST depression in V6. But there are also very deep S-waves in V3-V5 and a very tall R-wave in V6. The highest ST/S ratio is about 10% (normal).

There was an ECG from 4 months prior:

Atrial fib. QRS = 118 ms. Voltage was high then too, but ST segments were not. So the ST elevation is new.

The physicians were worried about this and showed it to me.

I said that this is very unlikely to be ischemia because of:

1) the severe cardiomyopathy
2) the high voltage
3) relative clinical stability in a patient with a baseline EF of 10%
4) presentation without chest pain

I recommended a bedside echo and further eval. This was done and showed very poor LVF and no WMA.

This actually represents a superimposed respiratory alkalosis: when the HCO3 = 45, the patient should compensate with a decrease in minute ventilation, such that the arterial pCO2 should be about 57 (0.9 x HCO3 + 15), and venous pCO2 should be slightly higher, around 62-64 mmHg, not 47 mmHg.

So the patient has profound metabolic disturbances [hypokalemic metabolic alkalosis without any respiratory compensation (and thus a superimposed resp alkalosis)], and this explains the ECG findings. After some treatment, this ECG was recorded 23 hours after the first:

It is normalizing

At 36 hours, after more electrolyte correction:

Looking more and more like the old ECG

At 3.5 days, there was some tachycardia:

This was diagnosed as SVT, but it is, in reality, sinus tachycardia. See image below with arrows.

Annotated

Arrows point to P-waves. Note the P-wave morphology, and PR interval, are the same as in the slower sinus rhythms.

Learning Points:

Cardiomyopathy, especially with metabolic derangement, can result in profound PseudoSTEMI patterns.

Sunday, May 10, 2015

This was sent to me by John Larkin, from Australia, who has a great ECG Blog called "ECG of the Week," where he posted it, and graciously allowed me to post it here.

The ECG is from an elderly male with multiple co-morbidities including significant cognitive impairment, cardiac failure and diabetes. He presented to the Emergency Department with several hours of chest pain and has a pacemaker in-situ for an unknown indication.

Here is his ECG:

John's thoughts on the ECG are as follows:

·Regular V-paced rhythm at 60 bpm with LAD.

·Lead V2 has concordant ST elevation but less than 1mm

·Lead V3 has excessive discordant ST elevation (ratio -0.33)

·Lead V4 has excessive discordant ST elevation (ratio -0.32)

·Lead V5 I suspect has excessive discordance but the baseline wander and native P wave superimposition makes it difficult to measure

·The T waves in leads V2-6 are huge compared with the QRS voltages

·Evidence of non-conducted native atrial activity

My thoughts

I was less certain of LAD occlusion because of the profound upward concavity, and I didn't think any lead met a consistent ratio of 0.25, though I think V3 did meet a ratio of 0.20. But was very suspicious of the very large T-waves.

One should keep in mind that in our LBBB studies (we have two now, with data forthcoming on the second, and larger, validation study) an ST/S ratio of 0.20 is more sensitive though slightly less specific, than 0.25.

But a ratio of 0.20 is still nearly 90% specific.

All this data is for LBBB and I do believe that it applies to paced rhythm.

Follow-up

The patient was not taken for angio given their extensive co-morbidities (including GI bleed) following discussion with both cardiology and patient’s family. He did have a troponin rise and was treated with maximal medical therapy.

Although he did not have an angiogram, followup ECGs, echos, and troponin prove that he did, indeed, have an LAD occlusion.

His initial troponin I was 6.7 ng/mL.

Echo showed EF of 30% with large amount of severe segmental systolic dysfunction.

This was 130 minutes later:

Now lead V4 has a ratio of 0.25

This was recorded at 6 hours:

The hyperacute T-waves are gone. The ST segments have nearly resolved.

This one is at 20 hours

Still more resolution of ST elevation and T-waves

T-wave starting to invert

In some data we have recently collected and will publish, we have shown that reperfusion of an occluded artery in LBBB, just like in normal conduction, results in reperfusion T-waves in many, if not most, cases.

A male in late middle age with a history atrial fibrillation, significant renal insufficiency, and implanted single chamber right ventricular pacemaker, but no known coronary disease, presented with 2 hours of sudden onset chest pain. It felt like heavy pressure. The pacer was placed 2 months prior, and the patient had no ECG recorded after placement to establish a baseline.

Here is his ED ECG:

There is a paced rhythm with proportionally discordant ST segments. There are no concordant ST segments. Thus, there is no evidence of STEMI.

Unlike Left Bundle Branch Block, there is comparatively little data on the accuracy of the Sgarbossa criteria in diagnosing acute MI (better, acute coronary occlusion) in the setting of a paced rhythm, and no data on the Modified Sgarbossa criteria. There are two small studies showing good specificity of the traditional Sgarbossa criteria, but poor sensitivity. There are 2 case reports (both by me and co-authors, references below) of STEMI diagnosed in paced rhythm by proportionally excessive discordant ST elevation (modified Sgarbossa criteria). I have posted other cases in which STEMI was easily diagnosed in the setting of paced rhythm. Here is one. Here is another. But we really don't know the sensitivity of concordant STE or proportionally excessively discordant STE in paced rhythm. I suspect it is as good in paced rhythm as in LBBB.

So the ECG in this case does not meet any Sgarbossa criteria

However, this patient has very suspicious symptoms and you do not want to miss a coronary occlusion.

So a bedside echo was done; here is the parasternal long axis view:

It looks as if the apex is not moving well.

Here is the apical view:

There is clearly an apical wall motion abnormality.

And this apical view shows the WMA clearly as well.

A review of the patient's chart showed that the last formal echo had been normal, but had also been done prior to placement of the pacemaker. Right ventricular pacing results in an abnormal sequence of activation and so there may appear to be a wall motion abnormality.

So the ECG shows no indication of occlusion, but the echo shows a new wall motion abnormality that can be completely due to the pacemaker.

The patient has a relative contraindication to coronary angiogram (renal insufficiency).

It was decided not to take the patient to the cath lab. Troponins were negative and the pain resolved.

Formal ultrasound done later had the same findings.

This ECG was recorded 4 hours after the first:

The T-waves are slightly taller, but there are no abnormal ST segments.

Learning points:
1. Use the modified Sgarbossa criteria in paced rhythms. The specificity is good. The sensitivity is unknown but probably similar to sensitivity in LBBB, which I believe to be as good as ST elevation in normal conduction, probably about 70-75% sensitive for coronary occlusion (though the sensitivity was much higher in our case control studies, which probably do not accurately reflect clinical practice).

2. The ECG in this instance was more reliable than formal echocardiography

Here is the ECG from the first case I link to:

This shows both concordant ST elevation in V2, and proportionally excessively discordant STE in V3. There is also concordant ST depression in V6.

One difference between LBBB and Paced rhythm is that, in paced rhythm, the QRS in V5 and V6 is almost always negative (but positive in LBBB). Therefore, any STEMI that manifests in V5 and V6 in LBBB will usually manifest by concordant ST elevation in these leads, whereas in paced rhythm, it must be excessively discordant ST elevation.

Sunday, May 3, 2015

An elderly male with end stage renal disease had hypotension (50's systolic) and syncope (LOC, and loss of radial pulses) during dialysis. He quickly regained consciousness. There was no chest pain or SOB. The patient has an implanted cardioverter defibrillator (ICD) due to previous cardiac arrest; it did not shock. His BP was 106/59 in the ED, with a pulse of 90.

He had a history of out of hospital cardiac arrest due to ventricular fibrillation and also recurrent ventricular fibrillation/polymorphic ventricular tachycardia, for which he received the Implantable defibrillator.

Previous echo had shown severe concentric LVH.

He also had a h/o CAD with PCI to mid LAD 2011.

Here is his ED ECG:

There is sinus rhythm with a wide QRS at 138 ms. It is very similar to LBBB, but because of Q-waves in aVL, it does not meet formal criteria. However, it is surely an intraventricular conduction delay, and all of the rules of appropriate discordance apply. Applying these rules, there is no concordant ST elevation. There is discordant ST elevation in V1-V3, and this was very concerning to the clinicians. It is not, however, out of proportion (ST/S ratio not greater than 0.25). The highest ST/S ratio is no more than 0.12, within normal limits. There is also high voltage.

Here is the most recent ECG from 6 months prior:

Sinus rhythm. QRS is 107 ms (much shorter). There is high voltage. There was much less ST elevation at this time, and the increased ST elevation concerned the clinicians. But the QRS is now wider too (new conduction delay) and the heart rate is also much slower and both of these can greatly affect the ST elevation. A faster heart rate generally exaggerates ST elevation in LVH, LBBB, and paced rhythm. Finally, the T-wave inversion in V4-V6 is deeper than typical for LVH. There is a very long QT.

Anterior STEMI is very unlikely here, even though the patient has a history of LAD CAD:

1) there is no chest pain or SOB
2) there is history of severe concentric LVH
3) there is appropriate and proportional discordance
4) the increase in ST elevation compared to the previous ECG can be explained by heart rate.

Nevertheless, there was still concern for anterior STEMI, so a bedside echo was appropriately done:

Here is the parasternal long axis:

This shows severe LV hypertrophy and good wall motion

A short axis echo was done:

This shows severe concentric hypertrophy and no wall motion abnormality.

This allayed fear of possible STEMI and a formal echo was done which also showed no wall motion abnormality. It confirmed severe concentric hypertrophy with a diastolic septum measurement of 1.76 cm (normal up to 11 mm)

The first troponin returned at 0.50 ng/mL (normal, less than 0.030). This patient frequently has troponins in the 0.12 - 0.16 range.

This ECG was recorded 8 hours later.

ST elevation persists, now with more upright T-waves

The next troponin was 0.41 ng/mL.

The syncope and hypotension was thought to be due to volume depletion from over-dialysis. The patient did well.

Learning Point

1. Severe concentric hypertrophy can result in many ECG abnormalities that mimic STEMI and NonSTEMI.
2. LVH may evolve into conduction delay (IVCD). The rule of appropriate discordance may come into play in IVCD and also in LVH.
3. Heart rate can affect ST segments, particularly in LVH, LBBB, and paced rhythm
4. Bedside echo can help in differentiating ischemic ST elevation from STE secondary to LVH or other etiologies.

Recommended Resources

Disclaimer

Cases come from all over the world. Patient identifiers have been redacted or patient consent has been obtained. The contents of this site have not been reviewed nor approved by Hennepin County Medical Center and any views or opinions expressed herein do not necessarily reflect the views or opinions of Hennepin County Medical Center.